A Brief Discussion on the analysis of the causes and solutions for SMT printed solder paste false soldering?

During the solder paste printing process, electronic components may fall off. In such a situation, how should it be solved? Now, the solder paste manufacturer will talk about some issues in this regard:

SMTAnalysis of the Causes of False Soldering of Printed Solder Paste 

1Generally speaking, the occurrence of false soldering may be due to insufficient solder or too many parts, or it may be caused by insufficient activity of solder paste or insufficient nitrogen concentration in the reflow soldering oven.

2Check whether there are any defects in the components, solder paste and operation process. 

3Check whether there is any abnormality in the solder paste printing machine equipment. 

4Consider opening holes in the expanded steel grating to increase the amount of solder paste used.

5During the reflow soldering process, it is very important to control the amount of solder paste used, positional deviation, temperature, etc. 

6The design of the soldered components and pads is unreasonable, resulting in offset during mounting. 

7,SMTThe protective wall was scraped off beyond the height of the part body. 

8The melting point of solder paste is lower than the temperature of wave soldering.

9,SMTMounting and welding, and tombstones.

10Parts damaged by external force in front of the wave soldering furnace.

11Thermal shock causes the components to break and fall off. 

This is where solder paste is prone to fall off during soldering11The main reason is that the control of solder paste soldering temperature is of great significance. The melting point of the solder paste is lower than the wave soldering temperature. Generally speaking, the melting point temperature of solder paste is220-240℃The wave soldering temperature is240-260℃Between. 

The temperature required for solder paste soldering is lower than that for wave soldering, which can prevent electronic components from being damaged due to excessive temperature, thereby improving the soldering quality and significantly reducing the probability of soldering failure. 

Besides,Solder pasteThe low temperature during welding can also reduce the toxic gases produced during welding, which is beneficial to environmental protection. Meanwhile, we also need to carefully inspect the solder paste printing to avoid waste and reduce the enterprise's costs.